Method of staining glass, glass staining compositions, and stained glass article



Patented Dec. 8, 1953 METHOD OF STAINING GLASS, GrAss STAINING COMPOSITIONS, AND STAINED GLASS ARTICLE Ormonde S. Levi, Toledo, Ohio, assignor to Verd- A-Ray Processing Company, Toledo, Ohio, a

corporation of Ohio No Drawing. Application May 13, 1953, Serial No. 354,894

- 32 Claims.

This invention relates to compositions and methods for staining glass and to the stained glass products thereby produced. More particularly, this invention is directed to the staining of soda-lime, borosilicate, lead glasses, and the like, and to the articles produced, such as stained flat ware, incandescent lamp bulbs stained to reduce the attraction of insects, for therapeutic or dark room uses, and the like.

This application is a continuation-in-part of my co-pending application Serial No. 153,749 entitled Stained Glass and Method of Staining Same, filed April 3, 1950, now abandoned.

The art.of staining to which the present invention is "directed comprises the coloration of a glass surface, and isnot to be confused with colored glass, wherein the molten glass batch is colored by the addition of suitable ingredients. In this connection, so-called stained glass windows are actually windows composed of small pieces of colored glass.

The art of staining glass with copper and/or silver compounds is several hundred years old. Usually the copper or silver salt, or both, is mixed with a suitable ochre or dispersing agent, and enough water added to provide a slurry of the desired viscosity. This slurry is then applied to the glass surfaceto be stained and the article is baked at a predetermined temperature to effect staining of the glass surface. The'excess fmud" is then removed by washing and scrubbing. Copper salts have been usedv alone on borosilicate glass to provide a yellow stain and, upon reduction of the copper, a red stain. 'No stain is obtained by copper salt alone on sodalime glass. Copper and silversalts have been used in combination with one another to produce amber stains on soda-lime glass, but these stainsare relatively light colored, being much too light for coloring incandescent light bulbs for therapeutic use. Also, the high temperatures required for effective staining using this stain composition, may deform the thin bulb as well as metallize the staining ingredientsthis latter eifectgreatly reducing'the amount of light and heat transmitted through the bulb.

In'spite of the long period in which glass stains havebeen known and used, and in spite of con siderable research upon staining compositions, the art of staining glass has advanced .so little since early times that only a very limited number of colors can be obtained. by staining, and only particular glass compositions can be used. It is for this reason that the art of staining glass is seldom practiced at the present time.

There are definite advantages, however, to staining glassware rather than coloring the entire glass batch as its now the usual practice. In the first place, partially finished glassware may" be colored to Order. This permits those manufacturers who provide finished articles to color their glassware independently of the operation of the manufacturer who produces the glass. 7

Also, large colored articles, such as stained glass windows, may be produced in one sheet of glass rather than the multi-pieced leaded windows now made, and at a lower price.

Although glass enamel is the customary medium for applying labels and for decorating glassware, stains may be readily applied and are much more permanent, lasting as long as the glass to which they are applied. This is especially important due to rigid State Statutes requiring the use of strong alkalisin cleaning bottles, etc., these alkali cleaning agents rapidly deteriorating the glass enamel but havinglittle or no effect upon the stain. The use of stains in decorating glassware, however, has been destricted due to the limited number of colors obtainableand inability to control these colors.

An object of this invention, therefore, is to provide compositions. and methods for staining glass in a variety of colors, and thus produce new and improved stained'glass articles.

Another object of this invention is to provide compositions and methods for staining glass uniformly and for producing a stain having an arcurately predetermined and reproducible color.

Still another object of this invention is to provide compositions and methods for staining several types of glass, such as soda-lime, borosilicate, lead glasses, and the like, in a variety of colors and in varying shades.

A still further object of this invention is to provide compositions and methods for staining soda-lime glass at temperatures below the softening point of the glass as well as the metallizing point of the stain composition, said stains being permanent, uniform and reproducible.

A still further object of this invention is to provide stained glass articles in a variety of colors and having accurately predetermined colors which are uniform throughout the stained area;

Still another object of this invention is to provide an amber lime glass and a method of making it that may be readily employed at a temperature low enough to avoid danger of deformation of thin glass, such as the walls of an incandescent lamp bulb, and still produce a deep amber stain satisfactory for therapeutic and dark room purposes.

An additional object of this invention is to providea method and composition for staining a borosilicate glass yellow, for'such use as in candescent bulbs, etc.

Other objects and advantages of this invention will become apparent to those skilled in the art from the following detailed description thereof.

3 THE INVENTION IN GENERAL It has been discovered that the combination of copper, silver and zinc salts in the presence of the chloride anion produces an active staining material for staining various types of glass. Furthermore, the color of the stain may be closely controlled by correctly proportioning the staining ingredients and by careful regulation of the baking temperatures.

To illustrate a staining composition representative of the present invention, the following example is set forth:

EXAMPLE 1 AgNO3 grams 1.2 ZnS do 9.0 CuCl do 13.0 Ochre do 80.0 (NI-I028 (45%) cc 29.0 Water cc 120 In addition to the active staining ingredients (AgNOa, ZnS, and CuCl) the above composition includes ochre, water and (NI-EMS.

The inclusion of ochre to disperse and to dilute the active staining material, and the use of water to provide a slurry of the desired consistency, represents the customary practice in the staining art. Other compounds, such as ammonium sulfide, sodium hydroxide, etc., may also be 9.1--

ployed to improve the uniformity of the stain as well as the depth of color. The variation of these dispersing agents to suit the particular use is well within the knowledge of one skilled in the art, so that detailed description thereof need not be included. The present invention is pri marily directed to the active staining ingredients themselves, and these ingredients will be described hereinafter in detail.

ACTIVE STAINING INGREDIENTS As above stated, copper, zinc and'silver salts combine, in the presence of the chloride anion, to produce an active staining material capable of staining various types of glass a variety of colors. Experimentation has shown that the anions of these metal salts, with the exceptions of the chloride anion, do not have any critical effect upon the staining characteristics of the combination, so that any of the salts of these metals may be used which will react with the chloride anion.

In Example 1, AgNOs, CuCl and ZnS are combined to produce a material capable of staining glass. A stain may be obtained from the combination of Zn, Cu and Ag chlorides, as well as from the combination of the nitrates, sul- EXAMPLE 2 Gus -grams 13.0 AgzS do 1.0 ZnS i do 9.0 Ochre dn 80.9 HCl (37%) ..cc 1.0 H20 Ace 100 The above composition baked onto soda-lime glass at 1000 F. produced a good green stain;

4. EXAMPLE 3 AgNOa "grams" 1.2 C1101 do 1.0 Cu(C2H302)2 dO 26.0 Z11(C2H302)z do 18.0 (NH4) 28 cc 4O Ochre grams 86 Water (to make a smooth slip, about 120 00.). A reddish amber was obtained on soda-lime glass at 1000 F. baking temperature. Without the CuCl, however, a dirty yellow color was obtained, due solely to the action of Cu and Ag.

EXAMPLE 4 AgNO3 grams 1.2 CuCOz do 13.0 ZnS do 9.0 (NHl) 2S C0 29 Ochre grams 80 HCl (37%) cc 2 Water to make a smooth slip.

A green stain was obtained on soda-lime glass at 1050 F. baking temperature.

EXAMPLE 5 Same composition as Example 4 except that an equal weight of CuSOr is substituted for the Water to make a smooth slip.

A mixture of red and green stain was obtained by baking this composition onto soda-lime glass at 1050 F.

EXAMPLE? AgNO3 grams 1.2 CuCldo 13.0 ZnCOs ido 9.0 (NI-I028 cc 29 Ochre grams 80 Water to make a smooth slip.

A very good light green stain was obtained on soda-lime glass at 1050 F. baking temperature.

Water to make a smooth slip.

A very good green stain resulted upon baking this composition on soda-lime glass at 1050 F. Here the chloride anion is furnished by the K61. Substitution of 3 grams of either KI or NHiHF: for the K01 in this composition destroys its staining characteristics, thus showing that the iodide and fluoride anions are not equivalent in this case to the chloride anion.

Although the salts of.copper, silver and zinc are generally applicable, salts wherein the metal cation predominates, or approximates 50% by weight of the salt, are much to be preferred over salts having extremely large anions. The reason for this preference is due to the dilution efi'ect of the large anions upon the concentration of the metal component or ion which effects the staining of the glass. Thus, the cuprous com+ pounds are preferred rather than the cupric because there is a higher percentage of copper'in the former than in the latter. Salts of the strong mineral acids are particularly satisfactory, since the anion portion of the salt is never materially heavier than the metal portion, and such salts are readily ionizable.

Since the copper, silver and zinc ions form the active staining portion of their respective salts, the relative amounts of these ingredients may best be defined by reference to the relative percentages by weight of copper, silver and zinc present, these percentages based upon the total weight of those three metal ions, calculated as metals.

Staining compositions can be obtained by combining Cu, Ag and Zn ions in widely varying proportions, and there are no sharp limits delineating compositions which will stain glass and those which will not. It is essential, however, that all three metal cations be present, since the absence of any one is fatal to the improved staining characteristics attained by the combinations of the three, as illustrated by the following examples.

Example 9 Example 10 Example 11 C 101.-- grams 0 l3 l3 AgNO: do 1.2 0 1.2 ZnS (10..-. 9.0 9.0 0 (NH )zS (45%) -cc. 29 29 29 Ochre .grams. 80 80 80 E .cc 120 120 120 Table 1 Example Percent Percent Percent number Cu Ag Zn Color of stem 0 89.0 11.0 No stain. 58.0 0 42. 0 Very light straw color. 91. 57 8. 43 0 Amber.

When copper was omitted no stain at all was obtained, while the omission of zinc produced merely the usual light amber stain from the copper-silver combination. The straw color obtained when silver is omitted is a very faint tint that may be due to the combination of zinc and copper or to slight impurities.

The addition of 0.2 gram AgNOx to the composition of Example No. 10, 0.25 gram of ZnS to the composition of Example No. 11, and 2 grams CuCl to the composition of Example No. 9, produced the remarkable stains recorded in Table 2, when the coated glass was baked at 1000 F. according to staining procedure above outlined:

It is apparent from Table 2 that as little as .875% Ag and 1.8% Zn will completely change the staining characteristics of the composition, since a green stain is obtained which is impossible to achieve by using any one of those metal salts alone or the combination of any two of these metal salts. The same remark applies to the yellow stain obtained by the addition of 15.8% Cu, since this yellow stain is completely diflerent from the amber obtained from the combination of copper and silver. By adding 5 grams CuCl in place of the 2 gram addition, a light medium red stain is obtained upon heating to 1000" F.

While the minimum amount of each of the three metal ions will vary slightly depending upon the other components of the staining composition, at least about .875% Ag, at least about 1.8% Zn, and at least about 15% Cu are required to produce an active staining material having the improved staining characteristics herein described. For preferred results, the lower limit of Ag should be about 2.5%; the lower limit of Zn should be about 20%; and the lower limit of Cu should be about 40%. Best commercial stains are produced when the Ag content is from 2.5% to 10%. The particle size of these staining ingredients is important, since larger particles do not react as quickly or as thoroughly as do the smaller particles. In the above example using 0.25 gram of ZnS, the particle size was -300 mesh. When a particle size of 150 mesh is used,

1 gram of ZnS is required to obtain a green stain.

The maximum amounts of each of these metal ions is established, in part, by the minimals of the other two, but over 21% Ag has no apparent beneficial efiect upon the staining properties of the composition. With the usual grade of zinc salts, such as ZnS, dependable stains are difficult to obtain when over 70% Zn is present, but the use of extremely finely divided ZnS, for example, permits as high as Zn to be employed. Cop per in amounts as high as may be employed, but about 85% Cu is preferred as an upper limit.

In addition to the copper, silver and zinc ions, it is necessary that at least a certain amount of a chloride compound be present. In the examples, above set forth, cuprous chloride usually furnished copper ions and constituted the chloride compound, although Example 2 and others show the addition of H01 for the latter purpose. Since, in the particular examples given, it is the chloride anion itself which is essential, the particular salt or acid which provides this anion is not critical. The most obvious procedure, of course, is the use of HCl or the chlorides of copper, silver or zinc. Chlorine gas can be used, but this gas forms I-ICl in aqueous solution and it is the chloride anion thus formed that is effective.

In determining the minimum amount of chloride anion required to develop the new and improved stain, 37% HCl in varying amounts was added to a base composition of 13 grams C118, 1 gram AgzS, 9 grams ZnS, 80 grams ochre and about cc. water. Table 3 shows the results of stain tests run on soda-lime glass at a temperature of 1000 F'., as above described, and the percent of chloride anion is based on total amount of Cu, Zn and Ag ions present, calculated as metals.

Table 3 Composition a Color Very faint straw color.

Base composition .l

4 Slight pale green.

Good green stein.

Base compos tion plus 1.0. Base composition plus 10.0

Do. 616% stain becoming darker.

agcca osuz Thespresence ot'ias littlesas 51.4% OI ChIOI'idGr anionicauses'aisli'ght gneenitotappear imthe stain-,3 showing; that "the :combinatiomof the1three metal. ions-:withrthe chloride anionisfbeginningito take effect; When 2i8%-"-chlor-ide anioniis-e resent; a 5 good green stain is'obtainedc I Additional amounts r of this 'ani'o'n: do not= produceanygmaterial' change. imtheistaining .:properties of -the-Fstain-i-composi tion: other than 5 a slight darkening, until the amount .thereof exce'eds v about 1 15 --based-uponthevtotal amount .-'of copper; silver and zinc; cab culated' as 'metals'. Chloride wanion: abovenabout: this wpercentage causes' etchingqof the =:glass- -.-anddeterioration oftthe stain color and is-,-ther.ef.ore;' undesirable: Accordingly anyyamount' of chlo-.- rine' from 1.4% to-Yabout 115 %=calculatedas indi:-- catedp-cis satisfactory. Ordinarilyyfor practical reasons fromabout- 2.8 to about 29% ci ch-1o;- rine .preferred';,

ADDITIONAL7 INGREDmN'rs FoiE sTAI-N COMPOSITION.

While .the active staining. ingredients may. be used by. themselves to produce a stain 'on'glass',.. much more satisfactory results are Obtained when other. ingredients .are addedfi Thus; .13 grams CfiClfd f2 grams .AgNO, .9 grams .ZnS'i'and'suffi cient water .to make .a slipiwere adrnixei' applied toiacsoda-li'me .glass surface. andfbak'ed to 105-0- Fftoiproduceadeep.greenstain. The glass sur- 0 face is etched;.h'ovvever,v and'a-more uniform stain of La. :good green. color is obtained. by, adding. ,80 gramsof ochre to..'thle-= above compositionz Ochre .isv a-. standard ingredient .fonmost stain compositions landiis .b'oth .cheap-v and.readily..avail: able. The primary; function of Qochre .is'..to..dis.- perse :and -to dilute=the .-active staining .ingredi; cuts; as welllas to-give body, to thesta-in. compositionnto. assist.in..its iapplic'ationitouthe. glass surface. The -composition..-of .theuochrei-usedin the .examples -set forthflinthisispecification-isas-- follows:

Percent Ferricoxide: -l f 52.52; Silica-ni ll .l 26.37- P Alumina; I. irosx Moisture e .81: Lesson ignition-. as- 9.25--

Theexact composition of theochre-"is amatterof choice, but a particular ochre 'should'besel'cted' and standardi'zed= if accurate repro ductionaor stain colors is =-to' beachieved; since the ochre compo sition'" does have some effect upon th e coldrof the I stain. The amount 0f "dispersing agent Will vary with-the composition-ofthe '-aotive -stain-'--- mg ingredients;- but must i be -control1ed' Within-' certain"limits, since an extremely Wide range may even vary thecolor of the stain','-due to the dilution effecti- Otherdispersing-agents may b'e-usedfbut ochre :is P prefer-red because of its low" costand (50 availability:

' In order to obtain the most 'l'desirable"deptlr'of'? color, it is preferable to add at least one oi -the metals, copper, silver "andi' zinc, as the sulphide.

Rather. tharnadd the metal as a sulphide per 5.

so, a sulphide may be added to a mixture of metal salts in amounts sufiicient to combine With one or'more-of'themetals? Best results 'are obtained" when sufilc'ient sulphide is added to combine.-

with all of the copper and silver present, 2.1-. 7

though very good results are obtained Whenla single metal is added as a sulphide,-. such aszinc: sulphide."- When the sulphide is added tothe= mixture of metal salts, a decomposable'sulphicla'. such as ammonium sulphide, is preferred. Howso ever, other/sulphides such as sodiumssulphidep mayrrbeaeuse'di: Toa-dategratheegreatestudepthilofu colors-has be'en .obtainedrwhentthe'zincrwas added: astzinc sulphide andzisufficient wammoniu'm'zsuls phide added to theoretically,combine*witlinallioii the;v copperfand zsilvempresents'. Effective sstaining: may: be-produced-gi however; without: ianyasuler phide presents.

The additiorrzofu aasl-ight aamount r of? sodium: hydroxide, such:--asi0;5%':orelessnhas been'ifoun'do in'xsomeiinstances'rtooassist in aproducing a u formusta'ing:.while'cin other :cases the'zadditivi preferably omitted. Although the exact .functionr of: the sodium: hydI'OXi'dii-SI10l7lkn0W1l317136 desirabilityi ofi'its use'zis ibelieved v:to' 'depend ruponil thezava'ilabilityiof sodium infthe .glassrsurface't be'stained-x Whenolittle 'csodiumr is 'zavailableeim; the-glass surfa'ce;:'theadditiomof sodiumchydroxa ideis recommendedo.

Water; is employed-.5 in zamounts r: sufficient 3 too f omit .the staining? compositionxzintora tslipi havw ing the-idesired consistency;- The .consiistenoyz onr viscosity of the staining slip will varyrwithrathez intended use. Whena fiat surfaceistobe stained, arelatively' 'thin or low viscosity slip maybe"employed"satisfactorily? Wloen'a"curvedsurface, such as a Iamp bulb, is -to be stained ia more viscous slip must be provided in order to be retainedin a uniform layer upon the curved-iisurface. The amount of water will'also vary: considerably with the particular ingredientsof the stain; Fori'examplesmuch 1ess: "-water:-:iszirequiredrfo stain in:whicheth'e dispersing gent or ochre has zsbeen omitted fthane ins-one rwh ich o -containsaaolargee-amount "0f OGhI efisince the fi amount of water requiredovaries with both: the: end use and the stain composition;incupracticai limitations therefor can. be set forth, but anyone skilled in the art*mayreadily determine by 40" routine experiment that. proportion of Water which ismost desirable-under any given circumstances.

METHODS OF. MAKING 'AND APPLYING-THE 'STAIN COMPOSITION The various ingredients of the --stain composition'may becombined by a number-of difierentprocedures, none of-..W-hich:-:appears:-to materially." afiect the stainingscharacteristiosmf -.the result-- ingfcomposition. One=procedureewhichahas ibeen l found .tobehighly-satisfactory:for preparing the": staining composition, isatogrind the-various com ponents of thestain in-.a ballamillcontaining porcelain :balls. The silver'ssalt if'sQIubIe andthe. sodium hydr0xi'de may.1be pace-dissolved and: added to the ball mill in sclutionform; Approx-1 imatelyhalf of thertotal amount :of. waterztebe addedato' the .COIl'lDOSltiOfizsiS eadded toe the :come. ponentsinrtheball: mill; The zstairuingredients are ground until they will pass through a 200- but 'th'e-igroundimixtur-eds driedtandsground wi-th oillto lproduceitheloil dispersion or oil-ibaseipaint;

The stain composition israpplied to the surface?- of. .'the article -to.-'b"e stained eitheribye dippinge. spraying, ,brusliingw. screening, or the dike The:

. dipping-procedure is fast and-adaptab1e*= torauto matic assembly line procedure. Control of the viscosity of the slurry, however, is required in order to obtain a coating of the stain composition of optimum thickness. When the stain coating or mud is too thick, cracks form during the baking procedure which ultimately show up in the finished article as unstained lines. If the slurry is too thin, the stain may not be continuous or may be too light due to low concentration of the active staining ingredients. Routine experiment will establish the satisfactory viscosity'for any particular operation. If the staining composition is to be applied by means of a brush or screen, as in the production of labels and the like, an oil base paint may be made by grinding the ingredients in oil.

In the baking operation, fairly close control of the temperature of the glass must be maintained to obtain the desired, predetermined color. The temperature employedwill be determined in part by the melting or softening point of the glass being stained, but temperatures in excess of 1100 F. destroy the staining composition by metallizing the metal salts. Since there is considerable lag in temperature rise between the oven air and the glass body, temperatures should be taken directly from the glass surface that is being stained. Indirect heating or heating by conduction is preferred to direct heating by radiation, since more uniform heat ing of all sides of the article to be stained may be obtained. In baking the mud coated article, the article is placed in an oven and heated slowly to a predetermined temperature, such as 900 F. If the glass article is relatively thin so that no strains will develop, it may then be immediately removed from the oven and allowed to cool in the air. For thicker articles, such as heavy bottles or flatware, cooling should be gradual. The mud is then removed by washing and brushing and the finished stained article obtained. Throughout this specification the staining temperatures specified are the temperatures to which the glass surface has been heated, and the above described staining procedure is employed unless otherwise stated.

For best results in staining aged glass or glass which contains decolorants, such as selen ium and antimony, a prebaking process is quite advantageous. The glass surface to be stained is heated to a temperature slightly in excess of thatv which is to be used in the staining operation and then allowed to cool. The heat treated surface may then be washed and is subsequently stained as above described. Much deeper stains Stain compositions comprising the present invention have the remarkable property of producing a variety of stains upon many different types of glass surfaces. Also, these stain compositions produce colors never before obtained in glass stains. Numerous factors are interrelated in determining the color of the stain produced. The respective amounts of the four active staining ingredients present, and particularly the amount of silver, plays a major role in color determination. The baking is another factor which may be employed to control the color of the stain. As above indicated, the amount and type of ochre, the type of glass, the presence of sulphides, and the particle size of the active staining ingredients also affect the color of the stain to a lesser degree, and so must be standardized to obtain careful color control and to reproduce a given color.

An amber color stain is obtained when the baking temperature ranges from 800 F. to 925 F., regardless of the particular amounts of the active staining ingredients. When the Ag ion is present in amounts over 21% (of Cu Zn, Ag

total), an amber is obtained at any baking temperature between 800 F. and 1100 F., the upper limit established by the decomposition'point of the staining ingredients. With staining compositions containing less than 21% Ag ion, a red or green stain is obtained at baking temperatures between 925 and 1100 F., depending upon the composition of the stain. Red stains may be obtained even with the lower amount of Ag ion, which usually produces a green stain, by carefully maintaining the baking temperature just below 1000 F., but such a procedure is difiicult to follow and mixed colors frequently are obtained. I

The predominant factor in controlling the color of the stain is the percentage of the three metal ions, Ag, Zn and Cu. To illustrate the effect of these metal ions on the color, a series of tests was run in which grams of ochre (composition above set forth) and 29 cc. of 45% (NH4)2S solution were employed in each composition. Soda-lime glass was used having an analysis of 73.50% SiOz, 1% R203, 16.5% NazO, 0.15% K20, 0.89% B203,4.82% CaO and 3.33% MgO. The following table shows the various formulations employed.

Table 4 v AgNOa ZIlS GU01 H20 r01 mula' number (grams) (grams) (grams) (cc.)

4. O 9. O 13. U 120 The various ingredients of the formulations shown in Table 4 above were ground to -200 mesh in a ball mill and the resulting slurry or mud applied to the soda-lime glass surface by dipping. A thermocouple embedded in the glass 1 1 adjacent the coated surface measured the temperature of the article when placed in a radiation type oven converted to indirect heating by placing slats in the front of the radiation elements. In each case, baking was halted as soon as the 1-2 The addition of-Zn from to- 74.6% -is-showng-in Formulae Nos. 19 to'29; inclusive. "I'he ZHSilSEd torthis series pf tests was too coarse topbtain the best resultsf so thatasa-consequence6:9% Zn was 5 required; to bta n -a-green sta1n. --Nored -sta1n glass surface reached 1000 F. ;After removal of was obtainedbecause-the Ag was alwaysless than the mud, the color of the stain was checked by 8.43%. -'Red-sta1nsare produced by the-add t on transmitted light, andthe followlng' results obof Znto compositions containing larger amounts tamed: of fig,- as 1s shown Formulae-Nos.- to' 42; 1n-

. Table 5 Btaking emggiln?. Peggznt Peg ent Percent pew Color i I ature,

,. 0 42. 0 58.0 1, 000 Very light straw Dirtyorfioggy. 875 '41: 6 "57. 525 1, 000 Light green 1. 7 Al, 3 57. 0 1,000 Bright yellow green- .3.4 40.6 56.0 1,000 .Goodrnedium green 5.04 39.85 55.01 1,000 Very good green 6.61 .39.25 54.114 1,000 Slightly darker green. 8.12 ,38. 63 53. 25 1,000 Mixed red and green Bed colorappearing andbecoming' stronger with green.

9. 37. 95 52. 46 l, 000 Same 10-92 37.43 51 65 12:38 36.81 '50. 81 Gradually diminishing. 13:. s 9.36,. 2v -50. o Beyond this,pdinti'littlaiignyhnprovementdev elops. 14.96 35.75 49.29- W l6, 3 35, 2 48. 5 17. 52 34, 65 V 47. 83 -21.0 32.2 45.8 I Amber stains gradually =deve1op fromthe red stains and'imprpye tofthispoint. Increased amounts ofsilver do not ir'nprove tho z -eplor. 26.1 31.1 "42.8 v 30.6 .292 .40.2 4.3 .27,7; 3 .0

- 8.43 0 91.57 81., 20 1,;80 90. 0 8. 1 3. 5 88. 4 0 7.8 6.9 85.3 7. 55 9. 95 82. 5 1,000 Red and green mixer 6.85 18.15 75.0 1,000 Red disappearing green e v 5.80 30.7 63.5 1,00 d0 5.01 40.0 55.0 1,000 Very good green 4. 4 47.0 48. 6 1,000 Color becoming muddy. 2. 5 69. O. 28. 5 1,000 Slight trace of green let 2.2 74.6 23.2 1, 000 N0 green but a stain exi t appearance. 5 11.0 89. 0 0 1, 000 No staining 7. 60. 4 32. 0 1, 000 Light medium red. I 5. 76 45. 82 48.142 1, 000 Green; 4. 64 36.78 58. 58 Very good green 3.89 30.9 65.2 d '21 5 i 0 78. 5 20. 2 1 5. 95 73, 85 17. 95 15. 95 66.1 Assuming a red'ton'e. 16.4 24. 2 49. 4 'Red becoming stronge 14.93 30.64 54.4 d 13. B6. 2 50. 3 l1 0 A8,. 6 40, 4 9. 5 55, 95 34-. 64 Sameas '41 Table, 5 shows clearly that a binary mixture ,of Cu and Ag (Nos. 35,.19) producesfonlythe, eX- ,fpected aniberstain, while binary mixtures of Cu iwith Zn -(No. 1). and' Zn with lAg (No.30) .pro- :.duce no. stain at all. I Formulae Nos. 1 1:018, inlclusiveqdisclose the efiect of increasing. thepercent of Ag ionfrom 4 to' 34.3%. Less than 1% Ag introduces a green colorlinto the stain, while fur- 1, ther additions up to about 8% darkens the-green: color. fI'he transitiompoint from green tored s from about 8% Ag to about 10% -Ag, and above 10% Ag but under 21% vAg produces'a red stain. Over 21% Ag an. amber stain is obtained, even jat a baking temperature of 1000..F., and little ,lchange isobtained by increasing the silver above this percentage.

' While this transition from green to red to -amber is truegenerallyof increased amounts of silverythe Ag% at which these changes occur .,w;i;ll..v ary;.sornewhat with theratio-oi Cu; to Zn. .For example, Formulae Nos. 12 .and -39 have a1'most identical, amounts of, silver, but a shift pf 75% less Zn :nd-5% more Cu decreasesthe-redi ness of the stain.

clusive. -Inthese compositionsL the color ofathe changes from;- ainber- -to-red-.asaltheezn. inereases-, -bnt; nq green appearsduetothe high-.perher tage ofsily'er. Large-e .mountsofeznaappear jtq reduoethe intensity of "the stain.

*-F ormu1ae;Nos. -;30 and 34; inclusive, show that inereasing amounts of Cu don-. .deepen -therstain and the larger amounts, 55.-% C=uand. above,:.are desirable. Preferably the Cu.;ion is present in an 7 Q ic -.th -.Zn '9 .b =eh 2 ins the deepest -,s ta s V s 11y -.obpained,whenrfihis rmxepori qnri r ned- "Therrfi m e rw thr h re eh rqre centages Mai-Ag 11 2 153 3 e en'e fl ldv broader .rang aofzAgaz fl use b eprebakme th glass surface. to.1'1.00:;F..and;then cooling. ;A- f ter washing the g1ass-.surface,-1athe stain -.composition is subsequently applied -in-accordanoe.with. this invention, and a very deep red may-be obtained.

,A seriesof tests wasrran to illustrate that Water insoluble chloride cornponnds; bothorganic and rinein producing stains according toithe .inve n 13 tion. In carrying out the tests the ingredients indicated in Table 6, below, were blended with 130 cc. of water and 80 grams of ochre of composition set forth above, and the resulting dispersion was applied to a soda-lime glass of analysis as set forth above.

14 bonate, in place of copper sulphide, silver sulphide, and zinc sulphide, no staining was observed. If however, Formula 48 is varied by replacing the silver sulphide, zinc sulphide, and copper sulphide by silver nitrate, zinc carbonate, and copper hydrate, a good yellow stain is produced. Although After application of the slurry, baking to 1000 F., and removal of the .mud as hereinafter described, the color of the stain produced, by each of the formulae set forth in Table 6 was checked by transmitted light. Formula 43 gave a commercially acceptable pale green stain. Formula 44, which is presented for purposes of comparison only, and is not within thescope of the invention because it contains no chloride compound, was a very pale straw color. Formula 45 produced definite staining of an amber color, and Formula 46 was a dark amber stain assuming a reddish tone. Formulae 47 and. 48 gave commercially satisfactory green stains. Formula 45 contained 1.67 per cent of chlorine based on the total of copper, silver and zinc, calculated as metals. Formula 43 contained 2.45 per cent of chlorine based upon the total of copper, silver and zinc, calculated as metals. It is usually preferred that the chloride compound employed be an inorganic chloride compound, although Formulas 47 and 48 in Table 6, above, show the use of organic chloride compounds. Most desirably, the chloride compound employed, in addition to being water soluble, is also ionizable so that, in water solution, it releases chloride anions.

The chemical mechanism which is responsible for staining of glass according to the method of the invention is not understood. It has definitely been established that each element of the combination of active staining ingredients is required. When water is used as the dispersing liquid it appears to be essential that there be a chloride compound dissolved in thcwater in the proportion above set forth. For example, when a staining technique was carried out identical with that described in connection with Formula 43, above, except that the CuS was replaced by copper hydrate, and the ZnS was replaced by ll. grams of zinc carbonate, substantially no staining was achieved. This result is explainable on the theory that the zinc sulphide used in Formula 43 reacted with the silver chloride to form silver sulphide and zinc chloride, and that the water soluble chloride compound (zinc chloride) is required for the desired result.

Similarly, virtually no color was observed when 2-ethylhexyl chloride was substituted for the benzyl chloride reported in Formula 48, and only a faint color when ethylene dichloride was substituted therefor. Also, when trichloroethane was substituted for the benzyl chloride of Formula 47, a light grey green color resulted. However, when ethylene chlorohydrin, which is readily soluble in water, was substituted for the benzyl chloride, a good green stain was achieved.

Furthermore, when Formula 47 was repeated using copper hydrate, silver nitrate, and zinc carthe invention is not limited to any theoretical explanation' suggested, it is believed that, when benzyl chloride is the sole source for chlorine in a staining composition, satisfactory results are achieved if there is a sulphide present because such sulphide must react with the benzyl chloride to release the chlorine therein in a water soluble form. When, however, water soluble trichloroacetic acid is employed as the source for chlorine, such reaction is not required for satisfactory staining.

Accordingly, it appears to be essential that the staining composition contain a water soluble chloride compound. It seems to be immaterial whether this water soluble chloride compound is organic or inorganic, although, as previously indicated, it is usually preferred to use an inorganic chloride compound for economic reasons. The water soluble chloride compound can be added as such, or can be formed in the aqueous dispersion by reaction between a water-insoluble chloride compound added, and some other ingredient thereof.

STAINING DIFFERENT GLASSES Stain compositions of the present invention are useful, not only in the staining of soda-lime glass, but other types as well, including lead glass, borosilicate glass, etc. Different colors are obtained on different types of glasses, as is shown in the following examples:

As shown in Tables 4 and 5 above, Formula No. 5, the above composition, produced a very good green stain on soda-lime glass. Following the same procedure on lead glass, the above composition produced a red stain. On borosilicate glass a yellow stain was obtained with the same stain composition and procedure.

7 7 EXAMPLE l3 CuCl grams l3 AgNOa do 3.6 ZnS do 9 (NI-I028 cc 29 Ochre "grams" H2O cc This stain composition (Formula No. 11 in Tables 4 and 5 above) stains soda-lime glass, red, while a yellow stain is produced on lead glass and borosilicate glass. In staining borosilicate glass,

,the :figmudicoatediglass1mavnbcloakedat: ll: 0;-F. :forltenvminutes to-,-pr,oducea verygood y llow :StaiILalISEf-MI in producing yellow colored-boro- -.silicate light:,bulhs,for example. t rshouldbe noted-,asa precaution in selecting,- aglasssurface .t,o:-be,; stained: thatglasses. containingedecoloring agents, such as antimony and selenium should be avoided, since these metals appear to interfere with the staining operation.

THE ARTICLE As has been above stated, the stained glass article produced in accordance with the present invention may be stained. a variety of colors which are distinct from those obtainable by use of prior art processes or compositions. Also, the raw article producedhas a different surfacecomposifies! ma ee m h c analysis ha stabl she the .exis en o t e ri an .ini h r las surface in additio n toCu and Ag. Zp 'doesnot appear intheglass surface, so that it must act ass, catalyst of sometype.

' gl-laving, described. the invention, iclaim:

;l. 'A, method of staining glass. surfaces which comprisesforming a finely divided, uniform aqueous dispersion containing copper, silver and zinc salts and a water-soluble chloride compoundin .amqyntssumcie lstainel nr qp tions such that, based on the total amount of coppen silver and zinc present, calculated as metaIs cQpper constitutes from about 15 per cent ,to about' QO per c ent, s ilver at least about 9.875 per cent, and; zinc atleast about 1:? per cent, and dissolved chlorine, basedon the total amountof copper, silverand zinc-present,calculated as metals, constitutes atleast 114 per centbut notmore -th an about;115 per cent, coating a glass surface with*a dispersioncontainingthe, copper, silver and zinc salts and the water-soluble chloride compound, and heating the coated glass surface to at least ;8 00,F.,ibutvnot=more-than1ll00 F. to pr duces sta ned a s i ac 2. A method ,of staining p a lime. glass surface whic ,cem rise f min a fi e divided .un feimas equ sdis sion on in up silver a i J m sul d a W te lu in r ani chloride compound in amounts sufficient to stain glass, and in proportions such that, based on the total amount of coppensilver and zinc present, calculated as metals, copper constitutes from ,about l5. per cent to about 90 per cent, silverat least about 0.875 per cent, and'zinc at least about ,1;.7 pencent, and dissolved chlorine, based onethe total amount of copper, silver and zincpresent, cadculated as metals, constitutes at least 1s per cent but notmore than about 115 per cent, coating -a lime glass-surfacewith said -dispersion, and heating the coated glass surface to atleast 800- F.,=-but -not-u1ore than 1100" F. to produce a stained glass-surface.

'3. A -n1ethod of staining a lead glass surface which comprises forming a finely divided, uniform aqueous dispersion containing'ooppen silver and zinc sulfides and ;,a water-soluble in- ,organic chloride compound in amounts sufficient ;to, stain glass, and in proportions such that, based on the total amount of copper, silver and zinc present, calculated as metals, copper constitutes ,from a bout l5 per cent to about 90 per cent silver ,atleast about 0.875 per cent, and zinc at least about 1;? per cent, and dissolved chlorine, based on the total'amount of copper, silver and zinc .present,-calculatedasmetals, constitutes at least 1.4 percent-but not-morethan about 115 per cent, coating a lead glass surface with said dis- Persian; and; eat nstthe, .coatekela susuzi ceet at least 800 but'not -more thanyllfifiiif' to .produce-a .Stainedg-lass surface.

Aye. :method of staining a ;;borosil icate;.glass ,suri cawhicncomprises f rmin a fi e divided,

uniform aqueous dispersion containing pcopper, silver and zinc sulfides and a water-soluble inorganic chloride compound in amounts sufiicient to stain glass, and in proportions such that,base'd von -the total amount of copper, .silver andgzinc lpresent calculatedasmetals, copper.. constitutes from about 1 -5;;per;, cent. .to,,a bout QO pencent, silver at least about0.875;;peracent, and zinc atleast about; 1 ;7; penpent, and'dissolved chlorine; base d gon the total amount of copper, silver and. -zinc present, calculated as metals,constitutes,;at'least 1,4 per cent but not more than about per cent, coating aborosilicate glass surfaceuwithsai'd dispersion, and heating the coated -glass--surface produce a stained glass surface.

--5. A; method of staining l-ime, lead-andiborosilicate glass surfaces which-comprises forming-a "finely divided, uniformaqueous flispersion con- 'taining copper, silver and zinc salts and-a Watersilver and zinc present, calculated as metals,,con-

stitutes at least 1;! per centrbutnotmore than about t 1 1-5 per cent, converting the copper, silver zinc salts in said dispersion toithe; respective sulfides, coating aglass surface with'saiddispersion, and heatingxthe coated glass surface to at-least 800 F.; but not more than 11 Q0 F.' to,pro duce, a stainedglass surface.

6. 'A method of staining lime; lead, andboros li as s face hichj cm ri e fq min fine d ded ,u ii rm a e u "dis rsion 'qnt min opp l ana-m zi c l anda w te bl in r ni hl rid .com cun dnemqunt s fl i t sta cl s i and in pnono tionssuch t-b Q1 th t elza ntof.connensilver nd in ,nmswt. alcu a e a ne al po pe constitutes from about 4 O.. per cent to ,about ;8 5

.; ntlve f qm smu 0, 7 pcrcentt ahqu 2 e -pent andzin a l a t.abqutllflrerrceut. and dissolved chlorine based onthe, total amount of copper, silver,,andzinc present, calculatedas metal s, constitutes ,at ,least ,2.8 per, cent hutnot more than about 115 per cent, coating a ,glass surface Withsaid dispersion,. and heating ,the coated glass surface toat ,lefist1800" Ftwb itnot more than 11 30" F. to produce a stained glass surface.

A e d of s i lime, l a .;an ihmc -silicate glass surfaces which comprises forming a fin ly d ed,- or a u ousp snersioncmwi n coroner. i v an .zin al s where n the copper, silver andzinc cations .constitutegt least about/5Q per cent of" the respective salts, anu a water soluble inorganic chloride compound in amounts suflicient' to, stain glass, and in propor- 'tions such that, based on 1 the total amount ,of

Copper, Silver a in pr sent, calculated a -metals,;copper constitutes fromabout f10 .per 0ent to about'85 per cent, silver from al )o ut,0 .8',75,per

p to about 21 percent, andzincatleastabout Use -"cent, anddis olvcd hlor ne. basedt n-she total amount of copper, silver and zinc present,

calculated as metals, constitutes at least 2.8 per cent but not more than about 115 per cent, coating a glass surface with said dispersion, and heating the coated glass surface to at least 800 F., but

not more than 1100 F. to produce a stained glass surface.

8. A method of staining lime, lead, and borosilicate glass surfaces which comprises forming a finely divided, uniform aqueous dispersion containing copper, silver and zinc salts of strong mineral acids and a water-soluble inorganic chloride compound in amounts sufiicient to stain glass, and in proportions such that, based on the total amount of copper, silver and zinc present, calculated as metals, copper constitutes from about 40 per cent to about 85 per cent, silver from about 0.875 per cent to about 21 per cent, and zinc at least about 1.7 per cent, and dissolved chlorine, based on the total amount of copper, silver and zinc present, calculated as metals, constitutes at least 2.8 per cent but not more than about 115 per cent, coating a glass surface with said dispersion, and heating the coated glass surface to at least 800 F., but not more than 1100 F. to produce a stained glass surface.

' 9. A method of staining lime, lead, and borosilicate glass surfaces which comprises forming a finely divided, uniform aqueous dispersion containing copper, silver and zinc sulfides and a water-soluble inorganic chloride compound in amounts suificient to stain glass, and in proportions such that, based on the total amount of copper, silver and zinc present, calculated as metals, copper constitutes from about 40 per cent to about 85 per cent, silver from about 0.875 per cent to about 21 per cent and zinc at least about 1.7 per cent, and dissolved chlorine, based onthe total amount of copper, silver and zinc present, calculated as metals, constitutes at least 2.8 per cent but not more than about 115 per cent, coating a glass surface with said dispersion, and heating the coated glass surface to at least 800 F., but not more than 1100 F. to produce a stained lass surface.

'10. A method of staining lime, lead, and borosilicate glass surfaces which comprises forming a finely divided, uniform aqueous dispersion containing copper, silver and zinc salts and a watersoluble inorganic chloride compound in amounts sufiicient to stain glass, and in proportions such that, based on the total amount of copper, silver and zinc present, calculated as metals, copper constitutes from about per cent to about 85 per cent, silver from about 0.875 per cent to about 21 per cent, and zinc at least about 20 per cent, and dissolved chlorine, based on the total amount of copper, silver and zinc present, calculated as metals, constitutes at least 1.4 per cent but not more than about 115 per cent, coating a glass surface with said dispersion, and heating the coated glass surface to at least 800 F., but not more than 1100 F. to produce a stained glass surface.

11. A method of staining lime, lead, and borosilicate glass surfaces which comprises forming a finely divided, uniform aqueous dispersion containing copper, silver and zinc salts wherein the copper, silver and zinc cations constitute at least about per cent of the respective salts, and a water-soluble inorganic chloride compound, in amounts sufficient to stain glass, .and in proportions such that, based on the total amount of copper, silver and zinc present, calculated as metals, copper constitutes from about 40 per cent to about per cent, silver from about 0.875 per cent to about 21 per cent, and zinc at least about 20 per cent,and dissolved chlorine, based on the total amount of copper, silver and zinc present, calculated as metals, constitutes at least 2.8 per cent but not more than about per cent, coating a glass surface with said dispersion, and heating the coated glass surface to at least 800 F., but not more than 1100 F. to produce a stained glass surface.

12. A method of staining lime, lead, and borosilicate glass surfaces which comprises forming a finely divided, uniform aqueous dispersion containing copper, silver and zinc salts of strong mineral acids and a Water-soluble inorganic chloride compound in amounts sufficient to stain glass, and in proportions such that, based on the total amount of copper, silver and zinc present, calculated as metals, copper constitutes from about 40 per cent to about 85 per cent, silver constitutes from about 0.875 per cent to about 21 per cent, and zinc at least about 20 per cent, and chlorine, based on the total amount of copper, silver and zinc present, calculated as metals, constitutes at least 2.8 per cent but not more than about 115 per cent coating a glass surface with said dispersion, and heating the coated glass surface to at least 800 F., but not more than 1100 F. to produce a stained glass surface.

13. A method of staining lime, lead, and borosilicate glass surfaces which comprises forming a finely divided, uniform aqueous dispersion con taining copper, silver and zinc sulfides and a water-soluble inorganic chloride compound in amounts sufficient to stain glass, and in proportions such that, based on the total amount of copper, silver and zinc present, calculated as metals, copper constitutes from about 40 per cent to about 85 per cent, silver from about 0.875 per cent to about 21 per cent, zinc at least about 20 per cent, and dissolved chlorine, based on the total amount of copper, silver and zinc present, calculated as metals, constitutes at least 1.4 per. cent but not more than about 115 per cent, coating a glass surface with said dispersion, and heating the coated glass surface to at least 800 F. but not more than 1100 F. to produce a stained glass surface.

14. A method of staining lime, lead, and borosilicate glass surfaces which comprises forming a finely divided, uniform aqueous dispersion containing copper, silver and zinc salts and a Watersoluble inorganic chloride compound in amounts SllffiClI1t to stain glass, and in proportions such that, based on the total amount of copper, silver and zinc present, calculated as metals, copper constitutes from about iilper cent to about 85 per cent, silver from about 2.5 per cent to about 21 per cent, and zinc at least about 20 per cent, and dissolved chlorine, based on the total amount of copper, silver and zinc present, calculated as metals, constitutes at least 1,4 per cent but not more than about 115 per cent, coating a glass surface with said dispersion and heating the coated glass surface to at least 800 F., but not more than 1100 F. to produce a stained glass surface.

15. A method of staining lime, lead, and borosilicate glass surfaces which comprises forming a finely divided, uniform aqueous dispersion oontaining copper, silver and zinc salts wherein the copper, silver and zinc cations constitute at least about 50 per cent of the respective salts, and a water-soluble inorganic chloride compound, in amounts sufficient to stain glass, and in proportions such that, based on the total amount of arena copper, silver and zinc present, calculated as metals, copper constitutes from about 40 per cent to about 85 per cent, silver from about 2.5 per cent to about 21 per cent, and zinc at least about 20 per cent, and dissolved chlorine, based on the total amount of copper, silver and Zinc present, calculated as metals, constitutes at least 2.8 per cent but not more than about 115 per cent, coa ing a glass surface with said dispersion, and heating the coated glass surface to at least 800 F., but not more than 1100 F. to produce a stained glass surface.

16. A method of staining lime, lead, and borosilicate glass surfaces which comprises forming a finely divided, uniform aqueous dispersion containing copper, silver and zinc salts of strong mineral acids and a water-soluble inorganic chloride compound in amounts suiiicient to stain glass, and in proportions such that, based on the total amount of copper, silver and zinc present, calculated as metals, copper constitutes from about 40 per cent to about 85 per cent, silver from about 2.5 per cent to about 21 per cent, and zinc at least about 20 per cent, and dissolved chlorine, based on the total amount of copper, silver and zinc present, calculated as metals, constitutes at least 2.8 per cent but not more than about 115 per cent, coating 2. glass surface with said dispersion, and heating the coated glass surface to at least 800 F., but not more than 1100" F. to produce a stained glass surface.

17. A method of staining lime, lead, and borosilicate glass surfaces which comprises forming a finely divided, uniform aqueous dispersion containing copper, silver and zinc sulfides and a water-soluble inorganic chloride compound in amounts sufficient to stain glass, and in proportions such that, based on the total amount of copper, silver and zinc present, calculated as metals, copper constitutes from about 40 per cent to about 85 per cent, silver from about 2.5 per cent to about 21 per cent, and zinc at least about 20 per cent, and dissolved chlorine, based on the total amount of copper, silver and Zinc present, calculated as metals, constitutes at least 1.4 per cent but not more than about 115 per cent, coating a glass surface with said dispersion, and heating the coated glass surface to at least 800 F., but not more than 1100 F. to produce a stained glass surface.

18. A method of staining a lime glass surface which comprises forming a finely divided, uniform aqueous dispersion containing silver sulfide and strong mineral acid salts of copper and since anda Water-soluble inorganic chloride compound, in amounts sufiicient to stain. glass, and in proportions such that, based on the total amount of copper, silver and zinc present, calculated as metals, copper constitutes from about 20 per cent to about 85 per cent, silver from about 2.5 per cent to about 21 per cent, and zinc at least about 20 per cent, and dissolved chlorine, based on the total amount of copper, silver and zinc present, calculated as metals, constitutes at least 1.4 per cent but not more than about 115 per cent, coating a glass surface with said dispersion, and heating the coated glass surface to at least 800 F., but not more than 1100 F. to produce a stained glass surface.

19. A method of staining a lime glass surface which comprises forming a finely divided, uniform aqueous dispersion containing silver sulfide and strong mineral acid salts of copper and zinc and a water-soluble inorganic chloride compound in amounts sufficient to stain glass, and

in proportions such that, based on the total amount of copper, silver and zinc present, calculated as metals, copper constitutes from about 40 per cent to about per cent, silver from about 0.875 per cent to about 21 per cent, and zinc at least about 20 per cent, and dissolved chlorine, based on the total amount of copper, silver and zinc present, calculated as metals, constitutes at least 1.4 per cent but not more than about 115 per cent, coating a glass surface with said dispersion, and heating the coated glass surface to at least 800 F., but not more than 1100 F. to produce a stained glass surface.

20. A method of staining glass surfaces as claimed in claim 1 wherein the uniform aqueous dispersion includes ochre.

21. A method of staining lime, lead, and borosilicate glass surfaces as claimed in claim 9 wherein the uniform aqueous dispersion includes ochre.

22. A method of staining lime, lead, and borosilicate glass surfaces as claimed in claim 13 wherein the uniform aqueous dispersion includes ochre.

23. A method of staining lime, lead, and borosilicate glass surfaces as claimed in claim 17 wherein the uniform aqueous dispersion includes ochre.

24. A stained glass produced by the method claimed in claim 1.

25. In a method of staining glass surfaces which comprises forming a finely divided, uniform aqueous dispersion containing, as active staining ingredients, copper and silver salts and a Water-soluble chloride compound in amounts sufficient to stain glass, coating a glass surface with said dispersion, and heating the coated glass surface to a temperature from about 800 F. to about 1100 F. to produce a stained glass surface,

. the improvement that consists in incorporating a zinc salt in the uniform liquid dispersion, and using the stated ingredients in proportions such that, based upon the total amount of copper, silver and zinc present, calculated as metals, copper constitutes from about 15 per cent to about per cent, silver at least about 0.875 per cent, and zinc at least about 1.7 per cent, and dissolved chlorine, based on the total amount oi copper, silver and zinc present, calculated as metals, constitutes at least 1.4 per cent but not more than about per cent.

26. In a method of staining glass surfaces the improvement as claimed in claim 25 wherein the uniform aqueous dispersion contains copper, silver, and zinc sulfides.

27. A method of staining glass surfaces which comprises forming a finely divided, uniform aqueous dispersion containing copper, silver and zinc salts and a water-soluble chloride compound in amounts sufficient to stain glass, and in proportions such that, based on the total amount of copper, silver and zinc present, calculated as metals, copper constitutes from about 15 per cent to about 90 per cent, silver at least about 0.875 per cent, and zinc at least about 1.7 per cent, and dissolve chlorine, based on the total amount of copper, silver and zince present, calculated as metals, constitutes at least 1.4 per cent but not more than about 115 per cent, drying the said dispersion, grinding the resulting dried composition with an oil to produce a uniform oil dispersion, coating a glass surface with said oil dispersion, and heating the coated glass surface to at least 800 F. but not more than 1100 F. to produce a stained glass surface.

28. A method of staining a glass surface which comprises forming a finely divided, uniform aqueous dispersion containing silver sulfide and strong mineral acid salts of copper and zinc and a water-soluble inorganic chloride compound in amounts sufiicient to stain glass, and in proportions such that, based on the total amount of copper, silver and zincpresent, calculated as metals, copper constitutes from about 40 per cent to about 85 per cent, silver from about 0.875 per cent to about 21 per cent, and zinc at least about 20 per cent, and dissolved chlorine, based on the total amount of copper, silver and zinc present, calculated as metals, constitutes at least 1.4 per cent but not more than about 115 per cent, drying the aqueous dispersion, grinding the resulting dried composition with an oil to produce an oil dispersion, coating a glass surface with said oil dispersion, and heating the coated glass surface to at least 800 F., but not more than 1100 F. to produce a stained glass surface.

29. A composition of matter for staining glass comprising a finely divided, uniform aqueous dispersion containing copper, silver and zinc salts and a water-soluble, chloride compound in amounts sufficient to stain glass and in proportions such that, based on the total amount of copper, silver and zinc present, calculated as metals, copper constitutes from about per cent to about 90 per cent, silver at least about 0.875 per cent, and zinc at least about 1.7 per cent, and dissolved chlorine, based on the total amount of copper, silver and zinc present, calculated as metals, constitutes at least 1.4 per cent but not more than about 115 per cent.

30. A composition of matter for staining glass comprising a finely divided, uniform aqueous dispersion containing copper, silver and zinc salts and a Water-soluble chloride compound in amounts sufiicient to stain glass, and in proportions such that, based on the total amount of copper, silver and zinc present,'calculated as metals, copper constitutes from about per cent to about per cent, silver from about 0.875 per cent to about 21 per cent, and zinc at least about 1.7 per cent, and dissolved chlorine, based on the total amount of copper, silver and zinc present, calculated as metals, constitutes at least 2.8 per cent but not more than about 115 per cent.

31. A composition of matter for staining glass comprising a finely divided mixture of copper, silver and zinc salts and a chloride compound which mixture, upon addition to water, forms a finely divided aqueous dispersion containing copper, silver and zinc salts and a water-soluble chloride compound in amounts sufficient to stain glass, and in proportions such that, based on the total amount of copper, silver and zinc present, calculated as metals, copper constitutes from about 15 per cent to about per cent, silver at least about 0.875 per cent, and zinc at least about 1.7 per cent, and dissolved chlorine, based on the total amount of copper, silver and zinc present, calculated as metals, constitutes at least 1.4 per cent but not more than about per cent.

32. A composition of matter for staining glass comprising a finely divided mixture of copper, silver and zinc salts and a chloride compound which mixture, upon addition to Water, forms a finely divided aqueous dispersion containing copper, silver and zinc salts and a water-soluble chloride compound in amounts sufiicient' to stain glass, and in proportions such that, based on the total amount of copper, silver and zinc present, calculated as metals, copper constitutes from about 40 per cent to about 85 per cent, silver from about 0.875 per cent to about 21 per cent, and zinc at least about 1.7 per cent, and

. dissolved chlorine, based on the total amount of copper, silver and zinc present, calculated as metals, constitutes at least 2.8 per cent but not more than about 115 per cent.

O'RMONDEL IS. LEVI.

No references cited. 

1. A METHOD OF STAINING GLASS SURFACES WHICH COMPRISES FORMING A FINELY DIVIDED, UNIFORM AQUEOUS DISPERSION CONTAINING COPPER, SILVER AND ZINC SALTS AND A WATER-SOLUBLE CHLORIDE COMPOUND IN AMOUNTS SUFFICIENT TO STAIN GLASS, AND IN PROPORTIONS SUCH THAT, BASED ON THE TOTAL AMOUNT OF COPPER, SILVER AND ZINC PRESENT, CALCULATED AS METALS, COPPER CONSTITUTES FROM ABOUT 15 PER CENT TO ABOUT 90 PER CENT, SILVER AT LEAST ABOUT 0.875 PER CENT, AND ZINC AT LEAST ABOUT 1.7 PER CENT, AND DISSOLVED CHLORINE, BASED ON THE TOTAL AMOUNT OF COPPER, SILVER AND ZINC PRESENT, CALCULATED AS METALS, CONSTITUTES AT LEAST 1.4 PER CENT BUT NOT MORE THAN ABOUT 115 PER CENT, COATING A GLASS SURFACE WITH A DISPERSION CONTAINING THE COPPER, SILVER AND ZINC SALTS AND THE WATER-SOLUBLE CHLORIDE COMPOUND, AND HEATING THE COATED GLASS SURFACE TO AT LEAST 800* F., BUT NOT MORE THAN 1100* F. TO PRODUCE A STAINED GLASS SURFACE. 